Cleavage fracture

Cleavage fracture is a sudden, smooth fracture without prior deformation. This happens when the structure is brittle, for example due to too rapid cooling during welding. Then hard, brittle martensite forms, and the cracked area breaks through suddenly. Make sure the component does not cool too quickly. For high-carbon steels, you must preheat and let it cool slowly after welding. Keep the weld clean and dry, because hydrogen makes the steel additionally brittle. If you don't pay attention to this, the part can break without warning, especially in cold.